The long range goal of the proposed research is to develop a comprehensive understanding of the key steps in the cell death program that is initiated as a part of normal development or as a consequence of teratogen-induced abnormal development. The purpose of this proposal is to establish a research program that will test the following hypothesis: teratogen-induced cell death and normal programmed cell death (PCD) are active processes associated with specific gene transcription and translation. A corollary hypothesis is: teratogen-induced cell death is an accentuation of programmed cell death. Based upon our extensive experience, we have selected several well studied teratogens, i.e., retinoic acid (RA), ethanol, hyperthermia, acetylaminofluorene (AAF), and cyclophosphamide (CP) and we will use them to induce cell death in rat embryos cultured in vitro. Our specific aims are: 1) to use available markers of cell death, i.e., cDNA and antibodies to c-fos, c-myc, hsp 70, TGF-beta1, TRPM-2, transglutaminase, and ubiquitin, to begin to assess their role in developmental PCD, i.e., PCD occurring in the interdigital areas of day 15 forelimb buds as well as PCD associated with ear and face development and 2) to use probes that are markers for developmental PCD to assess their role in teratogen-induced cell death. To accomplish these specific aims we will use various molecular methodologies including Northern and Western blots, in situ hybridization, and immunohistochemistry. The importance of the proposed research may be judged by the fact that 2-3% of all human neonates have clinically identifiable birth defects, defects that constitute the leading cause of infant mortality in the United States. Despite these statistics, information necessary to reduce the incidence of birth defects and related infant mortality is lacking. The proposed studies will contribute key information to the overall assault on the causes of birth defects.